I am unable to find the MO comments about the first use of the phrase "fat slags" in an article. On page 26 of this we find "these correspond to thickenings of the
corresponding special Lagrangian (giving fat SLags, as they are known in Britain,
or multiply-wrapped cycles in physics speak)."

As this arXiv paper is 2001, the whole business long precedes the beginning of MO in any case; what I remember is at least one comment expressing astonishment that the authors who invented the term fat SLags actually were able to put it in a real mathematics/physics paper without screams from a referee.

Anyway, this may be going into a survey talk for amateurs. Something juicy, you see.